How do I calculate my final average

1st Marking period 94
2nd -91
3rd-92
4th-88
Midterm-100
Final-50

The marking period average grades are worth 80% and the final and midterm are both worth 10% each toward the final grade.

.2(.94 + .91 + .92 + .88) + .1 + .1*.5 = x

.73 + .1 + .05 = x

.88 = x

88%

the formula for figuring out what you need on the final could be written as

.83 + .1x = y

where y = what grade you want (as a percentage)
x = what grade you need on the final

you have an 83% if you don't even show up to take the final
you have a 93% in the class if you ace the final

.83 + .1x = .9
.1x = .07
x = .7

you need a 70% on the final to get a 90% in the class

Take the percent of what you got on the evaluation, turn it into a decimal and multiply it by the amount it's worth as a percent.

Each marking period is worth 20%

0.94*20 = 18.8
0.91*20 = 18.2
0.92*20 = 18.4
0.88*20 = 17.6
1*10 = 10
.5*10 = 5

18.8 + 18.2 + 18.4 + 17.6 + 10 + 5 = 88% total

There are more advanced ways to do this, but I wanted you to understand.

I'm thinking you have a final grade in the 80's somewhere. Probably going to end up with a B. Should have tried harder on the final.

0.8*(94 + 91 + 92 + 88)/4 + 0.1*100 +0.1*50 = 0.2*365 + 10 + 5 = 73 + 15 = 88%